Abstract

Paleomagnetic data indicate that the Western Cascade Range from northern California to central Washington has undergone about 27° of clockwise rotation since 25 m.y. B.P. All the available regional paleo-magnetic data fit a two-phase rotation model, the first phase being an Eocene rotation that accompanied the accretion of the Oregon Coast Range to the continent and the second phase being a rotation associated with post–early Miocene extension in the Basin and Range province.